1 files changed, 18 insertions, 10 deletions

diff --git a/arch/s390/kvm/intercept.c b/arch/s390/kvm/intercept.c
index 9d19803111ba..98997ccba501 100644
--- a/arch/s390/kvm/intercept.c
+++ b/arch/s390/kvm/intercept.c
@@ -154,17 +154,25 @@ static int handle_stop(struct kvm_vcpu *vcpu)
 static int handle_validity(struct kvm_vcpu *vcpu)
 {
         int viwhy = vcpu->arch.sie_block->ipb >> 16;
+        int rc;
+
         vcpu->stat.exit_validity++;
-        if (viwhy == 0x37) {
-                fault_in_pages_writeable((char __user *)
-                                         vcpu->kvm->arch.guest_origin +
-                                         vcpu->arch.sie_block->prefix,
-                                         PAGE_SIZE);
-                return 0;
-        }
-        VCPU_EVENT(vcpu, 2, "unhandled validity intercept code %d",
-                   viwhy);
-        return -ENOTSUPP;
+        if ((viwhy == 0x37) && (vcpu->arch.sie_block->prefix
+                <= vcpu->kvm->arch.guest_memsize - 2*PAGE_SIZE)){
+                rc = fault_in_pages_writeable((char __user *)
+                         vcpu->kvm->arch.guest_origin +
+                         vcpu->arch.sie_block->prefix,
+                         2*PAGE_SIZE);
+                if (rc)
+                        /* user will receive sigsegv, exit to user */
+                        rc = -ENOTSUPP;
+        } else
+                rc = -ENOTSUPP;
+
+        if (rc)
+                VCPU_EVENT(vcpu, 2, "unhandled validity intercept code %d",
+                           viwhy);
+        return rc;
 }
 
 static int handle_instruction(struct kvm_vcpu *vcpu)